FI127762B

FI127762B - Method for producing porous composite material

Info

Publication number: FI127762B
Application number: FI20165699A
Authority: FI
Inventors: Minna Kellomäki; Kaarlo Paakinaho
Original assignee: Tty Saeaetioe; Tampereen Yliopisto
Priority date: 2016-09-19
Filing date: 2016-09-19
Publication date: 2019-02-15
Also published as: EP3515514A1; AU2017328807A1; CN110198746A; JP6985396B2; US20210228778A1; JP2019530792A; AU2017328807B2; FI20165699A; WO2018050969A1; AU2017328807C1; US11524094B2; CA3037449A1; CN110198746B

Abstract

The present invention relates to porous composite materials and objects such as 3D scaffolds, in particular to bioactive and bioresorbable scaffolds that can be transformed at body temperature.

Description

METHOD FOR PRODUCING POROUS COMPOSITE MATERIAL

FIELD

The present invention relates to porous composite materials and objects comprising the materials such as 3D scaffolds, in particular to bioactive and bioresorbable scaffolds that 5 can be transformed at body temperature. The present invention concerns also methods for producing the materials and use of the materials in tissue engineering.

BACKGROUND

Bone substitute materials derived from synthetic substances are promising technology challenging the traditional bone grafting in the field of regenerative medicine. An advanced io method for bone regeneration is to use tissue engineering methods that combine suitable cells together with bioactive and bioresorbable porous materials, i.e. scaffolds. In order to be used in regenerative surgery, the scaffold has to fulfil several requirements. For example, it should stimulate and support cell proliferation and tissue formation in three dimensional environments.

State of the art implantable porous 3D scaffolds suitable for bone substitute materials comprise either pure ceramic materials or biodegradable and bioabsorbable polymer containing bioactive ceramic particles dispersed therein.

Ideally, scaffolds for tissue regeneration should have the ability to be manipulated intraoperatively in order to adjust to the shape of the defect. Bioceramics are hard but brittle 20 and cannot be easily shaped according the operational need. They also lack of packing performance meaning that the optimal packing of particulates cannot be determined during operation. Hard particles do not form an effective interface with the native tissue, because they do not take shape according to the defects shape, i.e. they only form an interface with surrounding tissue from their comers and sharp edges. If porous materials consisting of pure 25 ceramic component are packed roughly, they can break and turn into smaller and denser materials. This can lead to complications during surgical operations and bone healing, because the loose particles cannot be squeezed together such that they would stay on the defect site. In such case the position of the defect can significantly effect on the operation technique, its ease and operation time, because loose and porous particles tend to flow 30 downwards due to gravitation.

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EP 1932550A1 discloses a composite porous object which comprises a biodegradable and biosorbable polymer containing bioactive bioceramic particles dispersed therein. Inner parts of the material have large voids having void diameter of 40-600 μίτι, and small voids having void diameter of 1 μηη or smaller.

US 8,119,152 discloses implantable bioactive material comprising organic-inorganic complex porous article in which bioactive bioceramics powder is uniformly dispersed in a biodegradable and biosorbable polymer. The material has continuous pores and the bioceramics powder is partly exposed to the pore inner surface or the pore inner surface and the pore article surface.

io Shikinami et al. [J. R. Soc. Interface, 2006, 3, 805-821, doi: 10.1098/rsif. 2006.0144] discloses a bioactive and biosorbable cellular cubic containing 70% by weight calcium phosphate in poly-D/L-lactide. According to the authors, the material has similar compressive strength and cellular geometry to cancellous bone. The material was osteoinductive, and it could be modified intraoperatively when heated above the Tg (65°C) 15 of the polymer.

One disadvantage of the composite 3D scaffolds of the art is that although they can be trimmed by using scissors and scalpels at room temperature, their transformation and insertion into bone defects requires heating the materials above their glass transition temperatures, such as to 70 °C. This may cause a heat sock to the site of defect during 20 operation. Furthermore, high implantation temperature makes the material unsuitable for use in methods where the material is to be inserted to the defect together with cells. According to Becker S. et al. (Spine 31, 1 January 2006 - Volume 31 - Issue 1 - pp 11-17 doi: 10.1097/01.brs.0000192762.40274.57) the bone formation is significantly increased when bone forming cells, e.g. from bone marrow aspirate, are impregnated into implantable 25 scaffold. The usability of patient’s own cells, harvested during the same surgical operation, accompanied by an osteoconducting or osteopromotive structure material presents a time and cost effective method for bone surgery.

Accordingly, there is a need for implantable scaffolds that could be transformed at significantly lower temperatures.

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SUMMARY

It was observed in the present invention that if a porous bioactive and bioresorbable scaffold, having overall porosity of 60-80 %, includes plurality, typically irregularly shaped, pores having average pore size between 200 and 500 gm, and wherein at least 50% of the pores 5 are connected to each other by channels wider than 5 gm, the scaffold can be modified by immersing into a fluid and/or by warming. Furthermore, the composite material stiffness can be reduced, elastic recovery speed increased, and the bioactive particles exposed from the polymer matrix by dynamically deforming e.g. by compressing the porous composite material of the present invention in a fluid.

io In accordance with the invention, there is provided a method for producing porous composite material comprising

a) providing composite material comprising bioabsorbable organic polymer comprising caprolactone, and 50-80% by weight of bioactive particles selected from bioceramic particles, bioactive glass particles and mixtures thereof,

b) saturating the composite material with CO2 under conditions wherein CO2 pressure is at least 74 bar and temperature is between 31 °C and melting temperature of crystalline phase of the organic polymer comprising caprolactone,

c) decreasing the CO2 pressure to 1 bar and keeping temperature between 31 °C and melting temperature of crystalline phase of the organic polymer, (d) immersing the porous composite material into a fluid and/or heating at 25-40 C°, (e) squeezing the porous composite material by subjecting to an external force, and (f) releasing the external force.

In accordance with the invention, there is provided also a new method for producing a porous composite object, the method comprising

a) providing an object comprising bioabsorbable organic polymer comprising caprolactone, and 50-80% by weight bioactive particles selected from bioceramic particles and bioactive glass particles,

b) optionally forming one or more holes to the object,

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c) optionally filling one of more of the one or more holes with bioactive particles selected from bioactive glass particles, bioceramic particles, mixtures thereof,

d) saturating the object with CO2 under conditions wherein CO2 pressure is at least 74 bar and temperature is between 31 °C and melting temperature of crystalline phase of the organic polymer, and

e) decreasing the CO2 pressure to 1 bar and keeping temperature between 31 °C and melting temperature of crystalline phase of the organic polymer (f) immersing the porous composite object into a fluid and/or heating at 25-40 C°, (g) squeezing the porous composite object by subjecting to an external force, and (h) releasing the external force.

In accordance with the invention, there is also provided porous composite object obtainable by a method according to any of claims 2-5.

In accordance with the invention, there is also provided porous composite object according to claim 6 for use in tissue engineering.

Further aspects of the invention are disclosed in dependent claims.

The verbs “to comprise” and “to include are used in this document as open limitations that neither exclude nor require the existence of un-recited features. The features recited in the accompanied depending claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of a or an, i.e. a singular form, 20 throughout this document does not exclude a plurality.

BRIEF DESCRIPTION OF DRAWINGS

Figure 1 illustrates a μ-CT photograph of an exemplary porous composite material according the present invention, figure 2 illustrates the decrease of compression modulus of an exemplary porous composite 25 material according the present invention when soaked in water (A = dry; B soaked for 48 h at 37 °C), figure 3 illustrates the strain/elastic recovery of an exemplary soaked and compressed composite porous material according the present invention,

20165699 prh 12-12-2018 figure 4 illustrates the decrease of elastic modulus of an exemplary porous composite material according the present invention (A = dry; B = wet and dynamically compressed for 10 min; C vacuum dried for 3 d after wetting and dynamically compressing), figure 5 presents structural changes in an exemplary composite material according to the present invention that occurs during deformation process from structure A (dry) to structure B (after wetting and compressing), and figure 6 presents structural change in a pore surface of an exemplary composite material according to the present invention due to the mechanical or dynamical deformation from the non-deformed structure A (pore comprising a polymer film) to structure B (the polymer film io broken by external force).

DESCRIPTION

According to one embodiment the present invention concerns a composite porous material comprising a biodegradable and bioabsorbable organic polymer comprising caprolactone, and bioactive particles dispersed therein. The overall porosity of the composite material is 15 60-80%, the average pore size is 200-500 pm, the content of the bioactive particles is 5080% by weight, preferably 50-70% by weight, and at least 50% of the pores are connected to each other by channels, wherein width of the channels is 5 pm or more. The pores are typically irregularly shaped.

The bioactive particles are selected from bioceramic and bioactive glass particles. According 20 to one embodiment, the bioactive particles comprise bioceramic particles. According to another embodiment the bioactive particles comprise bioceramic particles and bioactive glass particles. According to still another embodiment the bioactive particles comprise bioactive glass particles.

The biodegradable and bioabsorbable organic polymers used in the material are preferably 25 those which have ascertained to be safe. The organic polymer comprises caprolactone.

Caprolactone monomer is preferable due to its mechanoelastic nature as a component of the polymer chain, as well as its low glass transition temperature. As a structural component in lactide-based polymers, e.g. in poly-lactide-co-e-caprolactone copolymer comprising 70 molar-% L-lactide and 30 molar-% of ε-caprolactone (70L/30CL), the caprolactone parts of 30 the polymer chain generates significantly elastic nature to the material compared to polylactides comprising only L- or D-isomers of lactide.

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The biodegradable and bioabsorbable organic polymer of must include caprolactone. In addition to caprolactone, also further components can be present. According to an exemplary embodiment, the biodegradable and bioabsorbable organic polymer comprises caprolactone and one or more of: L-lactic acid, D-lactic acid, D/L lactic acid, glycolic acid, 5 blocks of L-lactic acid and D/L lactic acid, both lactic acid and glycolic acid, both lactic acid and p-dioxanone, both of lactic acid and ethylene glycol.

Exemplary polymers that may be present are polyglycolide (PGA), copolymers of glycolide, polylactides, copolymers of polylactide, unsymmetrically 3,6-substituted poly-1,4-dioxane2,5 diones, poly-3-hydroxybutyrate (PHBA), ΡΗΒΑ/β-hydroxyvalerate copolymers 10 (PHBA/HVA), poly-3-hydroxypropionate (PHPA), poly-p-dioxanone (PDS), poly-övalerolactone, poly-s-caprolactone, methylmethacrylate-N-vinyl pyrrolidine copolymers, polyesteramides, polyesters of oxalic acid, polydihydropyrans, polyalkyl-2-cyanoacrylates, polyurethanes (PU), polyvinylalcohol (PVA), polypeptides, poly^-malic acid (PMLA), polyβ-alkanoic acids, polyethyleneoxide (PEO) and chitine polymers. Copolymers of glycolide 15 comprise, for example, glycolide/L-lactide copolymers (PGA/PLLA) and glycolide/trimethylene carbonate copolymers (PGA/TMC). Polylactides comprise, for example, poly-L-lactide (PLLA), poly-D-lactide (PDLA) and poly-DL-lactide (PDLLA). Copolymers of polylactide comprise, for example, L-lactide/DL-lactide copolymers, Llactide/D-lactide copolymers, lactide/tetramethylglycolide copolymers, lactide/trimethylene 20 carbonate copolymers, lactide/ Ö-valerolactone copolymer, lactide/ ε -caprolactone copolymer, polydepsipeptides (glysine-DL-lactide copolymer), polylactide/polyethylene oxide copolymers and polylactide/polyethylene glycol (PEG) copolymers. A particular organic polymer is poly(lactide-co-s-caprolactone).

Exemplary bioceramic particles comprise unsintered and uncalcinated hydroxyapatite, a25 tricalcium phosphate (a-TCP), β-tricalcium phosphate (β-TCP), tetracalcium phosphate, dicalcium phosphate dehydrate, dicalcium phosphate anhydride, octacalcium phosphate or any of bioactive glasses. A particular bioceramic particle is β-TCP. The bioceramic particles and/or the bioactive glass particles are preferably granular, and the granule size is preferably 1-500 pm, more preferably 3-300 pm, most preferably 5-200 pm. The granulation is 30 preferable, since granulate particles have initially sharp edges that release the ions more rapidly than dense smoot surface. Naturally, also other shapes can be used.

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An exemplary porous composite material comprises β-TCP as the bioceramic material, and polylactide-co-s-caprolactone as the organic polymer.

According to one embodiment the biomaterial comprises bioactive glass particles. Bioactive glasses are a group of surface reactive glass-ceramic biomaterials and include the original 5 bioactive glass, Bioglass®. Exemplary bioactive glass particles suitable for the present invention are 45S5, 58S, 70S30C, and S53P4.

It is essential that at least 50 % of the pores of the composite porous material of the present invention are connected to each other by channels, and that the width of the channels is at least 5 pm, preferably from 50 to 150 pm. This is to ascertain the desired malleability of the io object and potential tissue and vascular ingrowth into the object and thus usability in tissue engineering. The porosity can be measured by high resolution micro-computed tomography (μ-CT). In the analysis the porosity is the total pore volume divided by total volume of the object. The pores can be extracted from the composite phase by thresholding the image stack to form binary image. Open porosity can be defined as all pores that are connected to 15 outside of the object divided by the total volume of the object. The pore network can be assigned so that each pore voxel has a value of the biggest sphere that it belongs to. Porosity is calculated by leaving out pores smaller than the current diameter. The result network is showing pores that are bigger than the current diameter. It means that a particle that has a size of current diameter can access all open porosity pores from outside of the 20 object.

According to one embodiment, the bioceramic particles are granular, and the particles are dispersed homogeneously to the polymer matrix. However, it is also possible that part of the particles is exposed on the pore inner surface and/or the porous object outer surface. This is advantageous for cell attachment and growth.

Figure 1 illustrates a μ-CT photograph of an exemplary object made of porous composite material according the present invention. The object shown therein was prepared by melt mixing poly-L-lactide-co-e-caprolactone 70L/30CL (PLCL), and β-tricalcium phosphate (βTCP) in melt extrusion process with the ratio of 50 weight-% of PLCL co-polymer and 50 weight-% of β-TCP with the granule size 100-300 pm. The composition was extruded into 30 rod shape. The composite rods were cut, placed into rod-shaped molds and foamed with supercritical carbon dioxide (ScCCh). After the composite rods were saturated with CO2 the pressure was decreased to the atmospheric pressure. The processing parameters including

20165699 prh 12-12-2018 time, temperature and pressure were optimized so that the desired pore size, pore connectivity and the channel width was obtained. The parameters affecting the pore generation are time used for CO2 diffusion or saturation into the polymer or composite structure, pressure, depressurization rate and process temperature. The time needed for 5 ScCO2 saturation is between 10 to 120 min, preferably between 40 to 90 min. The pressure needed for generating the pore structure is at least 74 bar, exemplary between 74 bar and 600 bar, preferably between 200 bar and 500 bar and the depressurization rate is in the range from 0.8 bar/min to 10 bar/min, preferably from 1.2 bar/min to 7 bar/min. The temperatures needed for the foaming process are between 3ΓΟ and the melting 10 temperature of the crystalline phase of the polymer. Exemplary temperature for melting the crystalline phase are 130 °C for PLCL 70/30 and 170 °C for P(L/D)LA 96L/4D.

Figure 2 illustrates the decrease of elastic modulus when the porous object of figure 1 is dynamically compressed after immersing to water, and figure 3 illustrates the strain/elastic recovery of soaked and compressed composite porous object. It was surprisingly found that 15 the modulus of the porous composite object of the present invention is lower when exposed to fluid than when dry. Accordingly, the elastic modulus decreased from 6 MPa to 4 MPa, and the material retains its original shape when the compression force is removed. This allows a fluid, in particular body fluid, such as blood and bone marrow aspirate, to be floated in the object. This is advantageous especially during surgical operations when for example 20 bone marrow aspirate or venous blood can be easily soaked to the porous object without additional complex instrumentation.

Figure 4 illustrates the decrease of elastic modulus when the porous composite object of the present invention is dynamically deformulated by compressing and immersing into water, and figure 5 illustrates how the dynamic compression affects the microstructure of the object. 25 In figure 4, bar A shows elastic modulus of a dry object. Bar B shows elastic modulus of the object after wetting and dynamically compressing for 10 min. Bar C show the situation when the object is vacuum dried after the wetting and compressing. Accordingly, the modulus is decreased ca. two orders of magnitude. The microstructure clearly changes during dynamic deformation from porous structure with smooth and solid polymer film covering pore 30 surfaces (Figure 5A) to porous structure with micropores or channels on the pore surfaces and ceramic particles exposed at least partly on the pore surfaces (Figure 5B). The change in the structure also affects the mechanoelastic properties of the porous composite due to weaker reinforcement of ceramic particles embedded in the polymer phase. The ultimate

20165699 prh 12-12-2018 strength and elastic modulus decreases and the porous composite object significantly softens at temperatures over 25°C as wet or dry. This enables an effective method to wet the sample by blood or bone marrow aspirate or other body fluid. The at least partly exposed bioactive particles such as bioactive ceramic particles increases biological activity of the 5 porous composite object, because the interaction between the bioactive particles such as bioceramic particles and the cells is more probable.

Figure 6 illustrates a pore of an exemplary composite object of the present invention, wherein the pore is covered by a PLCL 70L/30CL polymer film. Figure 6A shows a situation wherein the polymer film is intact, and figure 6B shows a situation wherein the film has been 10 broken.

Accordingly, the pore inner surfaces of the composite material and object of the present invention may be covered by a polymer film which can be broken by mechanical or dynamic deformation at temperatures ca. 25°C or higher as dry or wet. Accordingly, as shown in figure 6B, at least some of the ceramic particles embedded into the polymer matrix will be 15 exposed or detached from the composite structure or pore surfaces. This transformation of structure upon deformation can be advantageous to the cells proliferation and differentiation and thus tissue regeneration.

The porous composite object of the present invention has preferably a full elastic recovery from 50 % compression in about 0.5 - 60 minutes after compression. This property is 20 advantageous when the object is used e.g. for bone defect correction. Accordingly, the object can be squeezed and inserted into the defect, and while in place, the object is able to fill the defect entirely and form good contact with the surrounding bone tissue. Further advantage is that the structure of the porous composite object of the present invention is that when inserted in the bone defect, protuberances of the object can protrude the 25 surrounding bone pores when the compote material is recovering from compression. When plurality of objects is used for bone defect correction, the protuberances of one object can protrude to the pores of the second object during elastic recovery from compression. This advantageous property enables the formation of continuous porous matrix that is mechanically fused to one porous body.

According to another embodiment the present invention concerns a method for producing porous composite material, the method comprising

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a) providing composite material comprising bioabsorbable organic polymer comprising caprolactone, and 50-80% by weight bioactive particles selected from bioceramic particles and bioactive glass particles and mixtures thereof,

b) saturating the composite material with CO2 under conditions wherein CO2 pressure is at 5 least 74 bar and temperature is between 31 °C and melting temperature of crystalline phase of the organic polymer,

c) decreasing CO2 pressure to 1 bar and keeping temperature between 31 °C and melting temperature of crystalline phase of the organic polymer.

According to a preferable embodiment, the method further comprises:

(d) immersing the composite material into a fluid and/or heating at 25-40 C°, (e) squeezing the composite material by subjecting to an external force, and (f) releasing the external force.

Exemplary suitable fluids are alcohol such as ethanol and methanol, water, saline, and body fluid. Preferable body fluids are blood and bone marrow aspirate. According to a particular 15 embodiment the body fluid comprises cells, such as stem cells.

According to an exemplary embodiment the method comprises squeezing the object to a nonporous state by using an external force, and then releasing the external force so that the object returns to a porous state and the fluid, in particular body fluid absorbs to pores of the object. An exemplary force is 0.5 -100 N.

According to one embodiment the bioactive particles comprise bioceramic particles. According to a particular embodiment the bioceramic particles are granular, and the particles are dispersed homogeneously to the polymer matrix.

According to another embodiment the bioceramic particles are granular, and part of the particles are exposed on the pore inner surface and/or the porous object outer surface.

According to a particular embodiment the pore inner surfaces are covered by a polymer film, and the polymer film is at least partially broken upon deforming such as squeezing the porous composite object.

According to another embodiment the organic polymer comprises, in addition of caprolactone also further components. According to an exemplary embodiment, the

20165699 prh 12-12-2018 biodegradable and bioabsorbable organic polymer comprises caprolactone and one or more of: L-lactic acid, D-lactic acid, D/L lactic acid, glycolic acid, blocks of L-lactic acid and D/L lactic acid, both lactic acid and glycolic acid, both lactic acid and p-dioxanone, both of lactic acid and ethylene glycol.

According to one embodiment the bioceramic particles are selected from a group consisting of unsintered and uncalcinated hydroxyapatine, a-TCB, β-TCP, tetracalcium phosphate, dicalcium phosphate dehydrate, dicalcium phosphate anhydride, and octacalcium phosphate, preferably β-ΤΟΡ.

According to an exemplary embodiment the method for the preparation of an object made 10 of composite porous material of the present invention comprises melt mixing the bioabsorbable polymer and the bioactive material such as bioactive bioceramic particles, for example by extrusion into rod shape, foaming the composite structure into a porous composite structure by supercritical carbon dioxide and cutting the composite foam into desired shaped porous composite object.

According to a particular embodiment, the present invention concerns a method for producing of a porous composite object comprising

a) providing a composite object comprising bioabsorbable organic polymer comprising caprolactone, and 50-80% by weight bioactive partcles selected from bioceramic particles, bioactive glass particles and mixtures thereof,

b) forming, e.g. by drilling one or more holes to the object, and

c) foaming the composite object into porous composite object.

This method enables creating small directed holes in the composite porous object and/or heterogeneous areas into the material with high ceramic surface contact to the aspirated cells or ingrowing tissue.

The foaming is preferably performed by saturating the non-foamed object with CO2 under conditions wherein CO2 pressure is at least 74 bar and temperature is between 31 °C and melting temperature of crystalline phase of the organic polymer, and decreasing CO2 pressure to 1 bar and keeping temperature between 31 °C and melting temperature of crystalline phase of the organic polymer.

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According to another particular embodiment, the present invention concerns a method for producing a porous composite object comprising

a) providing a composite object comprising bioabsorbable organic polymer comprising caprolactone, and 50-80% by weight bioactive particles selected from bioceramic particles, bioactive glass particles and mixtures thereof,

b) forming, e.g. by drilling, one or more holes to the object,

c) filling the one or more holes with bioactive bioceramic particles, and

d) foaming the composite object into porous composite object.

This method enables creating areas with high ceramic content and passage to cells and 15 blood vessels into bigger size composite porous objects.

According to still another embodiment, the present invention concerns a method for transferring body fluid to the porous composite object of the preset invention, the method comprising (a) providing the porous object of the present invention, (b) immersing the porous object to the body fluid obtainable from a subject, (c) squeezing the object, preferably to a nonporous state by subjecting the object to an external force, and (d) releasing the external force so that the body fluid is absorbed to pores of the object.

Example 1

A polymer composite was prepared by melt mixing poly-L-lactide-co-e-caprolactone (PLCL), with the molar ratio of 70 % L-lactide and 30 % ε-caprolactone, and β-tricalcium phosphate (β-TCP) in melt extrusion process with the ratio of 50 weight-% of PLCL co-polymer and 50 weight-% of β-TCP with the granule size 100-300 pm. The composition was extruded into rod shape. The mixing ratio was assured by thermog ravi metric analysis. The composite rods

20165699 prh 12-12-2018 were cut, placed into rod-shaped molds and closed into a pressure vessel. The vessel was filled with CO2 and the pressure was increased to a range of 74 bar to 600 bar. The composite rods were saturated with CO2 for 30 to 90 minutes after which the pressure was decreased to the atmospheric pressure with the depressurization rate of 1.7 bar/min to 10 bar/min while keeping the temperature between 31 °C and melting temperature of the crystalline phase of the polymer. The porosity and pore size distribution were measured by micro-computed tomography. In the analysis the porosity is the total pore volume divided by the total volume of the object and the open porosity is defined as all pores connected to outside of the object divided by the total volume of the object. It is typical for the composite 10 to have a distinctive polymer film on the pore surfaces that covers the ceramic particles of composite. The foamed rods were cut to disk shape, packed and gamma-irradiated for sterility. Before implantation the porous composites were submerged to venous blood and dynamically compressed at room temperature. During the wetting and repeatedly compressing or squeezing the porous composite object the modulus decreased and the stiff 15 structure transformed into elastic, fully shape recovering, composite that was to soak the applied blood into it. Simultaneously at least some of the β-TCP particles embedded in the polymer matrix were exposed from the pore surfaces. A μ-CT photograph of an exemplary object prepared according to Example 1 is shown in figure 1 and the structural change during the compression is shown in Figure 5.

Example 2

A polymer composite was prepared by melt mixing poly-L-lactide-co-e-caprolactone (PLCL), with the molar ratio of 70 % L-lactide and 30 % ε-caprolactone, and β-tricalcium phosphate (β-TCP) in melt extrusion process with the ratio of 50 weight-% of PLCL co-polymer and 35 weight-% of β-TCP with the granule size 100-300 pm and 15 weight-% of bioactive glass 25 (45S5) with the granules size 100-300 pm. The composition was extruded into rod shape.

The composite rods were cut, placed into rectangular-shaped molds and foamed with supercritical carbon dioxide. The used foaming process temperatures were between the glass transition temperature and the melting temperature of crystalline phase of the polymer and the pressures were between 500 bar and atmospheric pressure. After the composite 30 rods were saturated with CO2 the pressure was decreased to the atmospheric pressure. The foamed rods were cut into block shape 20 mm x 20 mm x 6 mm submerged to ethanol for 30 min and then repeatedly compressed with over 50 % deformation ratio from different sides in order to expose at least part of the β-TCP and bioactive glass particles from the

20165699 prh 12-12-2018 pore surfaces. The samples were vacuum dried before packing and gamma sterilization. A μ-CT photograph of an exemplary object prepared according to Example 2 is shown in figure 5B

Example 3

A polymer composite was prepared by melt mixing poly-L-lactide-co-s-caprolactone (PLCL), with the molar ratio of 70 % L-lactide and 30 % ε-caprolactone, and β-tricalcium phosphate (β-TCP) in melt extrusion process with the ratio of 40 weight-% of PLCL co-polymer and 60 weight-% of β-TCP with the granule size 100-300 pm. The composition was extruded into rod shape. The mixing ratio was assured by thermogravimetric analysis. The composite rods io were cut, placed into rod-shaped molds and foamed with supercritical carbon dioxide. The used foaming process temperatures were between the glass transition temperature and the melting temperature of crystalline phase of the polymer and the pressures were between 500 bar and atmospheric pressure. After the composite rods were saturated with CO2 the pressure was decreased to the atmospheric pressure. The foamed rods were ground into 15 porous granules with the size of 1.4 mm - 2.8 mm.

Example 4

A polymer composite was prepared by melt mixing poly-L-lactide-co-e-caprolactone (PLCL) with the molar ratio of 70 % L-lactide and 30 % ε-caprolactone, poly-L/DL-lactide with the molar ratio of 70 % L-lactide and 30 % DL-lactide and bioactive glass in melt extrusion 20 process with the ratio of 40 weight-% of PLCL co-polymer 10 weight-% of poly-L/DL-lactide and 50 weight-% of bioactive glass (45S5) with the granules size 100-300 pm. The composition was extruded into rod shape. The composite rods were cut, placed into rodshaped molds and foamed with supercritical carbon dioxide. The used foaming process temperatures were between the glass transition temperature and the melting temperature 25 of crystalline phase of the polymer and the pressures were between 500 bar and atmospheric pressure. After the composite rods were saturated with CO2 the pressure was decreased to the atmospheric pressure. The foamed rods were cut into strip shape of 10 mm x 20 mm x 3 mm. The samples were vacuum dried before packing and gamma sterilization.

The specific examples provided in the description given above should not be construed as limiting the scope and/or the applicability of the appended claims.

Claims

PATENTTIVAATIMUKSET

1. Menetelmä huokoisen komposiittimateriaalin valmistamiseksi, joka käsittääA process for making a porous composite material comprising:

a) komposiittimateriaalin, joka käsittää kaprolaktonia sisältävän bioabsorboituvan orgaanisen polymeerin ja 50-80 paino-% bioaktiivisia partikkeleita, jotka on valittua) a composite material comprising a caprolactone-containing bioabsorbable organic polymer and 50-80% by weight of bioactive particles selected

5 biokeraamisista partikkeleista, bioaktiivisista lasipartikkeleista ja niiden seoksesta, hankkimisen,5 acquisition of bioceramic particles, bioactive glass particles and mixtures thereof,

b) kyseisen komposiittimateriaalin kyllästämisen CO2:lla olosuhteissa, jossa CO2:n paine on vähintään 74 bar ja lämpötila on 31 °C: een ja kyseisen orgaanisen polymeerin kidefaasin sulamislämpötilan välillä,(b) impregnation of said composite material with CO2 under conditions of at least 74 bar CO2 pressure and a temperature between 31 ° C and the melting point of the crystalline phase of said organic polymer;

10 c) CO2:n paineen laskemisen 1 baariin ja lämpötilan pitämisen 31°C:n ja kyseisen orgaanisen polymeerin kidefaasin sulamislämpötilan välillä tunnettu siitä, että menetelmä käsittää muodostuneen huokoisen komposiittimateriaalin (d) upottamisen fluidiin ja/tai lämmittämisen 25-40 0°: een, (e) puristamisen käyttämällä ulkoista voimaa, jaC) lowering the CO2 pressure to 1 bar and maintaining the temperature between 31 ° C and the melting temperature of the crystalline phase of said organic polymer, characterized in that the process comprises immersing the formed porous composite material (d) in a fluid and / or heating to 25-40 ° C. (e) extrusion by external force; and

15 (f) ulkoisen voiman vapauttamisen.15 (f) releasing an external force.

2. Menetelmä huokoisen komposiittikappaleen valmistamiseksi, joka käsittääA method of making a porous composite body comprising:

a) kaprolaktonia sisältävän bioabsorboituvan orgaanisen polymeerin ja 50-80 paino-% bioaktiivisia partikkeleita, jotka on valittu biokeraamisista partikkeleista, bioaktiivisista lasipartikkeleista ja niiden seoksesta, sisältävän komposiittikappaleen hankkimisen,a) providing a caprolactone-containing bioabsorbable organic polymer and a composite body comprising 50-80% by weight of bioactive particles selected from bioceramic particles, bioactive glass particles and mixtures thereof;

20 b) valinnaisesti yhden tai useamman reiän muodostamisen kyseiseen komposiittikappaleeseen,B) optionally forming one or more holes in said composite body;

c) valinnaisesti yhden tai useamman kyseisen yhden tai useamman reiän täyttämisen bioaktiivisilla partikkeleilla, jotka on valittu biokeraamisista partikkeleista, bioaktiivisista lasipartikkeleista ja niiden seoksesta,c) optionally filling one or more of said one or more holes with bioactive particles selected from bioceramic particles, bioactive glass particles and a mixture thereof;

25 d) kyseisen komposiittikappaleen kyllästämisen CO2:lla olosuhteissa, jossa CO2.n paine on vähintään 74 bar ja lämpötila on 31 °C:een ja kyseisen orgaanisen polymeerin kidefaasin sulamislämpötilan välillä,25 (d) impregnating said composite body with CO2 at a pressure of at least 74 bar and a temperature between 31 ° C and the melting point of the crystalline phase of said organic polymer;

e) CO2:n paineen laskemisen 1 baariin ja lämpötilan pitämisen 31°C:n ja kyseisen orgaanisen polymeerin kidefaasin sulamislämpötilan välillä tunnettu siitä, että menetelmä käsittää lisäksi (f) huokoisen komposiittikappaleen upottamisen fluidiin ja/tai lämmittämisen 25-40 C°:een,e) lowering the CO2 pressure to 1 bar and maintaining the temperature between 31 ° C and the melting temperature of the crystalline phase of said organic polymer, characterized in that the method further comprises (f) immersing the porous composite body in a fluid and / or heating to 25-40 ° C;

5 (g) puristamisen käyttämällä ulkoista voimaa, ja (h) ulkoisen voiman vapauttamisen.And (h) releasing the external force.

3. Patenttivaatimuksen 2, mukainen menetelmä tunnettu siitä, että fluidi on valittu alkoholista, vedestä, saliinista ja ruumiinnesteestä.The method according to claim 2, characterized in that the fluid is selected from alcohol, water, saline and bodily fluid.

4. Patenttivaatimuksen 3 mukainen menetelmä tunnettu siitä, että ruumiinneste on veri tai 10 luuydinaspiraatti.4. The method of claim 3, wherein the body fluid is blood or bone marrow aspirate.

5. Patenttivaatimuksen 3 tai 4 mukainen menetelmä tunnettu siitä, että ruumiinneste sisältää soluja.A method according to claim 3 or 4, characterized in that the body fluid contains cells.

6. Huokoinen komposiittikappale tunnettu siitä, että se on valmistettaessa minkä tahansa patenttivaatimuksen 2-5 mukaisella menetelmällä.A porous composite body characterized in that it is manufactured by a process according to any one of claims 2 to 5.

15 7. Patenttivaatimuksen 6 mukainen huokoinen komposiittikappale käytettäväksi kudosteknologiassa.The porous composite body of claim 6 for use in tissue engineering.